A sash window may comprise three functional parts: an upper sash, a lower sash, and a frame with opposing channels that encapsulate both the upper and the lower sashes. Both the upper and the lower sashes slide within the channels on either side of the frame. A relatively equal amount of force may actuate a sash if the friction against the channel-frame is also equal. However, the relative friction within each channel may not always be equal and may change due to externalities, such as weather or contaminants, including dirt or paint. If an equal amount of force is applied to either side of the sash that has an unequal amount of relative friction, one side of the sash may move more quickly than the other. In this case, the sash may twist, and the friction within the channel of the frame may increase above the forces being applied to each side of the sash. Thus, the sash may bind against the frame and not continue to progress within the channel.
Conventional systems have attempted to address the need to maintain an appropriate force against each side of the sash in order to successfully actuate the sash. However, these devices have attempted to mechanically link the mechanisms applying the force on either side of the sash. In at least one conventional system, the force is applied at the center of the sash, thereby also obstructing the opening. In this last example, the force applied to the center is expected to propagate equally to the sides of the sash without significant twisting within the frame. This is not always the case, as only a minor amount of friction differential to one side may initiate a twisting that may quickly cause the sash to bind within the channel. A controlled application of force close to the axis of the channels may ensure a smooth and successful actuation of the sash.